The publication “Adaptive Fahrgeschwindigkeitsregelung ACC” (Adaptive Cruise Control ACC), published by Robert Bosch GmbH, April 2002 (ISBN-3-7782-2034-9) discusses a radar sensor and a method for operating this radar sensor, frequency-modulated radar signals being transmitted and partial waves reflected by objects within the sensor detection range being received. The mixing of the transmitted and received signals gives rise to frequency signals representing a linear combination of relative speed and distance of the detected object. The use of a plurality of rising and falling frequency ramps makes it possible to superpose a plurality of linear combinations containing the relative speed and the distance of the object, resulting in an unambiguous point of intersection of these straight lines which represents the actual relative speed and the actual distance of the object. The use of a plurality of rising and falling frequency ramps having different slopes makes it possible to resolve any ambiguities occurring even if a plurality of objects are present in the sensor detection range.
A disadvantage in this related art may be that when a rising and a falling frequency ramp having a first slope and a rising and falling frequency ramp having a second slope are used per measuring cycle, i.e., a total of four frequency ramps is used, the computing complexity for determining the relative speed and the distances of a plurality of detected objects makes it necessary to have enormous computing capacity for analyzing the linear combinations. If, for example, a total of eight objects is detected within a measurement cycle having four frequency ramps, then 8*4=32 straight lines and 84=4096 straight line intersections result, which must be checked with regard to objects actually present or with respect to apparent objects, since it is not known in advance which straight-line points of intersection represent real objects. If the number of detected objects increases, the computing complexity increases accordingly by a power of four, making expensive and complex evaluation devices necessary.